In recent years, increases in the number of wireless communication devices and the like using high frequency bands and increases in communication speeds have inevitably led to higher frequency bands being widely used. Along with this, there is a demand for circuit substrates having a small dielectric tangent to reduce transmission loss at high frequencies as much as possible.
Examples of resin materials used for such circuit substrates include the cyclic olefin copolymers obtained by copolymerizing a diene described in Patent Document 1 and Patent Document 2.
Patent Document 1 and Patent Document 2 disclose that a sheet obtained by cross-linking a cyclic olefin copolymer obtained by copolymerizing a specific diene compound with an organic peroxide or the like exhibits excellent dielectric characteristics.
Furthermore, Patent Document 3 discloses resin compositions including a cyclic olefin copolymer obtained by copolymerizing a specific diene compound and various resins. However, Patent Document 3 does not disclose any techniques regarding specific measures for improving the dielectric characteristics.